An extension of covered areas in a wireless network or an increase of a bandwidth of the wireless network are occasionally achieved by an “extension of the wireless base station” or a “change of the wireless parameter” in the wireless base stations even after starting an operation of the wireless network, which includes a plurality of wireless base stations to executes a wireless communication between users.
FIG. 1 is a block diagram showing a configuration of the conventional wireless network. The wireless network shown in FIG. 1 includes a wireless base station 101, a wireless base station 102, a network 103, and a wireless network management section 104. The wireless network management section 104 is managed by a wireless network service provider. The wireless base station 101 and the wireless base station 102 are managed by the wireless network management section 104 through the network 103. A covered area and a bandwidth are set as wireless parameters in each of the wireless base station 101 and the wireless base station 102. The covered areas as a wireless network are areas to be covered by each wireless base station included in the wireless network. Here, the wireless base station 101 has a covered area 101a with the bandwidth that can accommodate three user terminals. Moreover, the wireless base station 102 has a covered area 102a with the bandwidth that can accommodate three user terminals.
In FIG. 1, user terminals 201, 202 and 203 in the wireless network exist in the covered area 101a. The wireless base station 101 accommodates the user terminals 201, 202 and 203. User terminals 206, 207 and 208 exist in the covered area 102a. The wireless base station 102 accommodates the user terminals 206, 207 and 208. Each user terminal is exemplified by a mobile terminal such as a cellular phone and a PDA (Personal Digital Assistant), and a personal computer of note type. The user terminals 204 and 205 exist in the covered area 101a covered by the wireless base station 101, they, however, are not accommodated by the wireless base station 101 since the bandwidth of the wireless base station 101 has no capacity. User terminals 209, 210 and 211 never be accommodated in the wireless network, since they are not included in neither the covered area 101a of the wireless base station 101 nor covered area 102a of the wireless base station 102.
FIG. 2 is a block diagram showing another configuration of conventional wireless network. FIG. 2 shows an example where a wireless base station 105 is added on the configuration shown in FIG. 1 in order to extend the covered area in the wireless network. In FIG. 2, the same code is referred to the same item as the one in the configuration in FIG. 1. In FIG. 2, the added wireless base station 105 has covered areas 105a, and has a bandwidth enough to accommodate three user terminals. User terminals 209, 210 and 211 are to be accommodated in the wireless network because of the extension of the covered area by adding the wireless base station 105.
FIG. 3 is a block diagram showing further another configuration of a conventional wireless network. FIG. 3 shows an example where a bandwidth of the wireless base station 101 is increased by changing the wireless parameter of the wireless base station 101 in FIG. 1. In FIG. 3, the same code is referred to the same item as the one in the configuration shown in FIG. 1. In FIG. 3, the wireless base station 101 has the bandwidth enough to accommodate five user terminals by changing the wireless parameter. As a result, the user terminals 204 and 205, which are not accommodated by the wireless base station 101 in the configuration shown in FIG. 1, are accommodated by the wireless base station 101.
FIG. 4 is a block diagram showing further another configuration of a conventional wireless network. FIG. 4 shows an example where the wireless parameter of the wireless base station 101 shown in FIG. 1 is changed to extend the covered area 101a of the wireless base station 101 and to increase the bandwidth of the wireless base station 101. In FIG. 4, the same code is referred to the same item as the one in the configuration shown in FIG. 1. In FIG. 4, the covered area 101a of the wireless base station 101 is extended and the wireless base station 101 achieved to have enough bandwidth to accommodate seven user terminals by changing the wireless parameter. As a result, it is possible to further accommodate the user terminals 204, 205, 209 and 210.
In a conventional technique, when executing the “extension of the wireless base station” or the change of the wireless parameter of the wireless base station as shown in FIGS. 2, 3 and 4, a simulator is used, so that the extension of the covered area of the wireless network or the increase of the bandwidth of the wireless network are calculated, and proposals regarding the “extension of the wireless base station” or the change of the wireless parameter of the wireless base station are made based on the calculation result. Then, the proposals are provided to the wireless network service providers.
Incidentally, the wireless network service providers take income by charging a use fee based on the traffic load of the users who are accommodated in the wireless network. On the other hand, an operation cost of the wireless network is expenditure. The difference of the income and the expenditure is the profit of the wireless network service provider.
In conjunction with the above description, Japanese Laid Open Patent Applications JP H08-317458A and JP 2001-285923A discloses a technique by which the wireless network service providers decides an arrangement pattern of wireless base stations in consideration of there own profits.
Japanese Laid Open Patent Application JP H08-317458A discloses a method for deciding the arrangement pattern of a PHS base station. In the method of deciding the arrangement pattern of the PHS base station, first, a plurality of various arrangement pattern of the PHS base stations is prepared for a predetermined service planning area. Next, a simulation of an electric field strength distribution is carried out on each of the arrangement patterns. Continuously, the ratio of the dimension of a call-possible area to the dimension of the service planning area is calculated as a quality assessment value in every arrangement pattern based on the simulation result. Afterwards, a cost evaluation value is calculated in every arrangement pattern. Then an arrangement pattern for the service planning area is decided from all arrangement patterns based on the quality assessment value and the cost evaluation value for each arrangement pattern.
Japanese Laid Open Patent Application JP 2001-285923A discloses a method for deciding a base station arrangement pattern. In the method for deciding a base station arrangement pattern, first, a map of a target area, which includes data of shape of buildings that influences transmission of an electric wave, is prepared for the base station arrangement. Next, places, in which the base stations can be arranged, are detected from the prepared map. Then, each of the places is specified as a base station candidate point where the base station will be arranged. Further, area evaluation points, which are given discretely as evaluation positions of reception ability, is specified in order to specify a communication possible area in the target area for the arrangement of the base station. Afterwards, electric power, which is received at each of the area evaluation points, is calculated in the case that the base station would be arranged at one of the base station candidate points, for every base station candidate point. Based on this result, the communication possible area is specified in the case that the base station would be arranged at one of the base station candidate points. However, the communication possible area is given as a collection of the area evaluation points that are judged as communication possible positions in which the received electrical power is larger than the predetermined threshold. Afterwards, a gene information expression form is selected, which corresponds to a combination of the base station candidate points to arrange the base station. An evaluation function corresponding to the purpose for the base station arrangement is set with that. A genetic algorithm is applied to search the gene information that maximizes the adaptation given by the evaluation function, then, an optimal base station arrangement pattern is decided.
These techniques provide an arrangement pattern of the wireless base station and an arrangement cost as data to decide an arrangement pattern of the wireless base stations. The arrangement pattern is decided based on a simulation. The arrangement cost is a cost needed to achieve the arrangement pattern. However, only the information concerning the expense of the wireless network service provider is provided as information concerning the profit of the wireless network service provider.
The profit of the wireless network service provider is obtained by subtracting the expense from the income. Therefore, if there is no information concerning the income when the wireless network is changed, it is difficult for the wireless network service provider to decide the change in the wireless network taking consideration in their own profit. That is, these techniques have a difficulty to provide a change proposal for the wireless network to improve the profit margin of the wireless network that is an end goal of the wireless network service provider.
In conjunction with the above description, Japanese Laid Open Patent Application JP H08-322079A discloses a method for deciding an arrangement position of an extensional base station in PHS. The method for deciding an arrangement position of an extensional base station in PHS decides the arrangement position of the extensional base station to extend the PHS base station in a service area in which one or a plurality of PHS base station is arranged. First, the electric field strengths are measured in the plurality of points in the above-mentioned service area. Next, parameters of a mathematical model is adjusted so that the electric field strength distribution in the above-mentioned service area, which is calculated by a simulation using the above mentioned mathematical model, matches the electric field strength distribution by the measurement result of the above-mentioned electric field strength as much as possible. Continuously, parameters concerning an extensional base station including the parameters concerning arrangement positions for the extensional base station are given to the mathematical model after the parameters are adjusted in order to simulate the electric field strength distribution in the above-mentioned service area when assuming that the extensional base station is arranged. Afterwards, the simulation result is evaluated. The parameters concerning the extensional base station are changed after repeating the above-mentioned each process, parameters concerning a suitable extensional base station are decided based on the evaluation results of each parameter concerning the extensional base station.
Japanese Laid Open Patent Application JP H06-188817A discloses a method for arranging wireless base stations. In the method for arranging a base station, each wireless base station is arranged in which intervals of micro cell base stations are in inverse proportion to bias of the traffic load so that the traffic load covered by each cell becomes approximately equal. The method tries to make a communication quality of a reverse link be constant in a code division multiple access mobile communication system.
Japanese Laid Open Patent Application JP 2003-8498A discloses service area examination system. The service area examination system executes a measuring of service area, an optimization, and a managing of a newly extended base station. The service area examination system includes an area measuring apparatus, a mobile communication system, a network, and a server. The area measuring apparatus calculates the service area based on a simulation result, and moves in the service area to execute various measurements and optimization of the base station. The data processing base station communicates with the area measuring apparatus for data processing. The mobile communication system includes the newly extended base stations and a plurality of control bureau to control the newly extended base stations. The network is connected with the mobile communication system. The server is connected with the network to analyze measurement data transmitted from the area measuring apparatus, then, provides the processing result to the area measurement apparatus. The area measurement apparatus adjusts a parameter and an antenna tilt of the newly extended base station based on the processing result from the server by a remote control.
Recently, the charge for use of the wireless network has been decreasing in recent years. Therefore, it is very important for the wireless network service provider to suppress an investment and operation cost of the wireless network and increase a profit margin, satisfying demands of the users of the wireless network and the communication quality. It is desired to propose the “extension of the wireless base station” and the change of the wireless parameter of the wireless base station by which the profit margin of the wireless network is maximized.